This invention relates to shift bracket assemblies for use on shift rails of manually operated transmissions. More particularly the invention relates to shift bracket assemblies wherein spring loaded plungers are employed to assist in the movement of gear shift levers, and to provide or enhance physical sensing of lever position.
Prior art shift bracket assemblies have incorporated direct or "in-line" spring-loaded plungers, in combination with angularly off-set spring and poppet ball systems. The latter spring and poppet ball systems have been employed only to "spring lock" such plungers in their most outwardly or extreme positions. While the latter shift bracket assembly has been and is yet satisfactory in the operation of the lowest ratio gears of heavy duty truck transmissions, the in-line forces associated therewith have been unsatisfactory in shifting among the top end or highest ratio gears, the latter being more frequently utilized in over highway situations.
Those skilled in the art will appreciate that shift levers contain shift fingers which engage axially movable rails for effecting gear changes. There exists a strong preference for lighter shift lever control forces as related to shifts involving the highest ratio gears. This is because it is generally easier for a driver to pull a shift lever transversely toward his right knee (viz toward the first and reverse shift rail in most truck environments) than to push the lever away (viz toward the highest ratio shift rail) under an identical spring force. Thus, in over-the-road shifting in hilly areas, a lighter spring return force is desirable in association with the frequently utilized highest ratio shift rail.
The most commonly utilized prior art shift bracket assembly requires two separate spring systems in its normal operation, and is thus more complex and expensive to manufacture. Thus, a bracket is needed which will provide lighter spring return forces in shifts between highest ratio gears, and which, preferably, is also simpler and less expensive to manufacture.